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Antibiotics for C. Difficile (OpTION Trial)

Phase 4
Research Sponsored by VA Office of Research and Development
Eligibility Criteria Checklist
Specific guidelines that determine who can or cannot participate in a clinical trial
Must have
Confirmed current diagnosis of CDI, determined by having >3 loose or semi-formed stools for participants over 24 hours AND Positive stool assay for C. difficile EIA positive for toxin A/B; or Cytotoxin assay; or Nucleic Acid Amplification Test (NAAT, PCR or LAMP) based detection of toxigenic C. difficile
>3 loose or semi-formed stools for participants over 24 hours
Must not have
Acute or chronic diarrhea due to inflammatory bowel disease or other cause (e.g., presence of an ileostomy or colostomy) that would confound evaluation of response to CDI treatment
Receipt of >72 hours of antibiotics considered effective in the treatment of CDI, including: metronidazole, vancomycin, fidaxomicin, nitazoxanide, rifaximin
Screening 3 weeks
Treatment Varies
Follow Up day 90 since randomization
Awards & highlights


This trial will compare two different treatments for recurrent Clostridium difficile infection, to see which is more effective.

Who is the study for?
Adults over 18 with a confirmed first or second recurrence of C. difficile infection within the past 3 months, who have had more than three loose stools in 24 hours and can provide informed consent. Pregnant or nursing women are excluded, as well as those allergic to vancomycin or fidaxomicin, on long-term antibiotics, with severe CDI symptoms like hypotension or ileus, other causes of chronic diarrhea, prior extensive treatment for CDI, active COVID-19 (unless recovered), and inability to take oral medication.Check my eligibility
What is being tested?
This study is testing if treating recurrent C. difficile infections with either fidaxomicin alone or vancomycin followed by a tapering dose of vancomycin is more effective than just standard vancomycin treatment. Participants will be randomly assigned to one of these treatments to compare outcomes.See study design
What are the potential side effects?
Potential side effects from the medications may include nausea, vomiting, abdominal pain and discomfort. Vancomycin might also cause kidney issues in rare cases while fidaxomicin could lead to allergic reactions.

Eligibility Criteria

Inclusion Criteria

You may be eligible if you check “Yes” for the criteria below
I have been diagnosed with CDI, with symptoms and positive stool test results.
I have had more than 3 loose stools in the last 24 hours.
I am older than 18 years.
I am not pregnant or breastfeeding.

Exclusion Criteria

You may be eligible for the trial if you check “No” for criteria below:
I have ongoing diarrhea not related to CDI that could affect treatment evaluation.
I have taken antibiotics for over 72 hours to treat CDI.
I have severe intestinal issues including very low blood pressure, blockage, or a rapidly swelling colon.
I have taken more than one course of specific antibiotics for a C. diff infection.


Screening ~ 3 weeks
Treatment ~ Varies
Follow Up ~day 90 since randomization
This trial's timeline: 3 weeks for screening, Varies for treatment, and day 90 since randomization for reporting.

Treatment Details

Study Objectives

Outcome measures can provide a clearer picture of what you can expect from a treatment.
Primary outcome measures
Determine symptom resolution during treatment without any of the following: diarrhea recurrence; other non-fatal clinical events including severe abdominal pain, toxic megacolon, and colectomy; and death.
Secondary outcome measures
C.diff Health Related Quality of Life (HRQOL)
CDI Composite outcome measure
Diarrhea Composite outcome measure
+4 more

Trial Design

3Treatment groups
Experimental Treatment
Group I: Vancomycin T/PExperimental Treatment1 Intervention
Standard 10-day vancomycin treatment followed by taper and pulse vancomycin treatment for Clostridium difficile
Group II: VancomycinExperimental Treatment1 Intervention
Standard 10-day vancomycin treatment for Clostridium difficile
Group III: FidaxomicinExperimental Treatment1 Intervention
Standard 10-day fidaxomicin treatment for Clostridium difficile
First Studied
Drug Approval Stage
How many patients have taken this drug
Completed Phase 4
Completed Phase 4

Find a Location

Who is running the clinical trial?

VA Office of Research and DevelopmentLead Sponsor
1,628 Previous Clinical Trials
3,325,430 Total Patients Enrolled
Stuart B. Johnson, MD BAStudy ChairEdward Hines Jr. VA Hospital, Hines, IL
Dale N Gerding, MDStudy ChairEdward Hines Jr. VA Hospital, Hines, IL

Media Library

Fidaxomicin (Anti-bacterial) Clinical Trial Eligibility Overview. Trial Name: NCT02667418 — Phase 4
Clostridium Research Study Groups: Fidaxomicin, Vancomycin, Vancomycin T/P
Clostridium Clinical Trial 2023: Fidaxomicin Highlights & Side Effects. Trial Name: NCT02667418 — Phase 4
Fidaxomicin (Anti-bacterial) 2023 Treatment Timeline for Medical Study. Trial Name: NCT02667418 — Phase 4
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